In a manifold reactor which is designed to purify exhaust gases by reburning them, the engine exhaust is introduced thereinto through a plurality of port liners. These port liners are inserted into the reburning chamber through the engine cylinder head fixture. One end of the port liner is supported at the cylinder head fixture which is the base point, while its other end is fitted to the gas-seal collar of the outer shell of the reburning chamber in the manifold reactor. Otherwise, the port liner is supported by an external protective casing with a heat insulator between them.
Such a method of support has the drawbacks that, when the port liner is long, the gas-seal collar suffers deformation or wear due to engine vibration; in consequence the heat-insulating material escapes through a fine gap between the sealing ring and the port liner into the manifold reactor and disperses therein, resulting in a drop in the purifying efficiency and other undesirable phenomena.